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Polyethylene compositions having improved printabilityRelated Patent Categories: Synthetic Resins Or Natural Rubbers -- Part Of The Class 520 Series, Natural Rubber Compositions Having Nonreactive Materials (dnrm) Other Than: Carbon, Silicon Dioxide, Glass Titanium Dioxide, Water, Hydrocarbon, Halohydrocarbon, Ethylenically Unsaturated Reactant Admixed With A Preformed Reaction Product Derived From: (a) At Least One Polycarboxylic Acid, Ester, Or Anhydride; (b) At Least One Polyhydroxy Compound; And (c) At Least One Fatty Acid Glycerol Ester, Or A Fatty Acid Or Salt Derived From A Naturally Occurring Glyceride, Tall Oil, Or A Tall Oil Fatty Acid, At Least One Solid Polymer Derived From Ethylenic Reactants Only, Polymer Mixture Of Two Or More Solid Polymers Derived From Ethylenically Unsaturated Reactants Only; Or Mixtures Of Said Polymer Mixture With A Chemical Treating Agent; Or Products Or Processes Of Preparing Any Of The Above Mixtures, Solid Polymer Derived From Ethylene Or PropylenePolyethylene compositions having improved printability description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060217490, Polyethylene compositions having improved printability. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The invention relates to polyethylene compositions. More specifically, the invention relates to polyethylene compositions having improved printability obtained by incorporating polyethylene glycol and modified polyethylene components therewith and to the process for obtaining the improved compositions [0003] 2. Description of the Prior Art [0004] Polyethylene (PE) resins are widely used for the production of films, laminates and extrusion coatings in view of their ready processability, low cost and physical properties. However, due to the non-polar nature of the polymers and the smooth, non-porous nature of the surface of films, laminates and coatings produced therefrom, printability is poor. [0005] Various post-treatment techniques have been employed to modify the surface characteristics, i.e., increase surface energy, of polyethylene substrates to improve printability, wettability and adhesion. Such post-treatment procedures have included corona discharge, flame treatment, ozone treatment, plasma treatment and various chemical treatments. [0006] Whereas post-treatment procedures of the above types can enhance printability, they require additional steps in the manufacturing process. This not only requires additional capital outlays for the purchase, modification and maintenance of equipment but also can limit line speed. [0007] It would be highly advantageous and desirable if polyethylene compositions which inherently exhibited improved printability and eliminated the need for post-treatment in all but the most critical applications were available. It would be even more desirable if these compositions were produced using economical and readily available components. These and other objectives are achieved with the compositions of the invention. SUMMARY OF THE INVENTION [0008] The invention relates to polyethylene resin compositions having improved printability comprised of 85 to 98.75 weight percent, based on the total composition, polyethylene base resin, 0.25 to 5 weight percent, based on the total composition, polyethylene glycol having an average molecular weight from 500 to 20000, and 1 to 10 weight percent, based on the total composition, modified polyethylene resin containing carboxylic acid or carboxylic acid derivative functionality. More specifically, the polyethylene base resins employed for the invention are ethylene homopolymers or copolymers of ethylene and C.sub.3-8 .alpha.-olefins having densities from 0.890 to 0.970 g/cm.sup.3 and melt indexes from 0.01 to 40 g/10 min. Particularly advantageous base resins include linear low density polyethylene having a density from 0.906 to 0.930 g/cm.sup.3 and melt index from 0.1 to 10 g/10 min., high density polyethylene having a density from 0.945 to 0.965 and melt index from 0.05 to 15 g/10 min., and low density polyethylene having a density from 0.910 to 0.930 g/cm.sup.3 and melt index from 0.5 to 20 g/10 min. [0009] Highly useful compositions are obtained utilizing polyethylene glycols having average molecular weights from 1000 to 6000 and modified polyethylene resins grafted with 0.2 to 4 weight percent maleic anhydride. It is particularly advantageous when the modified polyethylene resin is high density polyethylene or linear low density polyethylene grafted with 0.2 to 4 weight percent maleic anhydride. [0010] To obtain compositions having improved printability the base resin, polyethylene glycol and modified polyethylene are subjected to what is referred to herein as reactive compounding, that is, the components are combined and melt blended under conditions of mixing and shear to effect an increase in melt elasticity. The reactive compounding operation increases the melt elasticity of the melt compounded product by at least 20% and, more preferably, 25% or more over that of the base resin. Articles fabricated from compositions produced in the above manner consistently exhibit improved ink adhesion. DETAILED DESCRIPTION OF THE INVENTION [0011] Compositions of the invention which exhibit improved adhesion with commonly used inks contain 85 to 98.75 weight percent (wt. %) polyethylene resin, 0.25 to 5 wt. % polyethylene glycol and 1 to 10 wt. % modified polyethylene. Compositions obtained by blending 90 to 96 wt. % polyethylene resin with 0.5 to 4 wt. % polyethylene glycol and 2.5 to 7.5 wt. % modified polyethylene are particularly advantageous. Weight percentages of the above components are based on the total weight of the composition. [0012] Polyethylene (PE) resins employed for the invention, also referred to herein as the base resin since they constitute the major component of the blends, include ethylene homopolymers, ethylene-C.sub.3-8 .alpha.-olefin copolymers and mixtures thereof. Additionally, minor amounts of other ethylene polymers may be included in the base resin. The particular base resin employed will depend on the intended application, i.e., whether the final composition will be extruded or cast into film, extrusion coated, injection molded, blow molded or the like, and the physical, chemical and rheological characteristics required for processing, fabrication and durability of the finished product. [0013] Useful polyethylene resins for the base resin component(s) can include very low density polyethylene (VLDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE and mLLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE) and very high or ultra high molecular weight polyethylene produced using known polymerization catalysts and procedures. The polyethylene resins can be produced using Ziegler catalysts or single-site catalysts. Metallocene single-site catalysts are transition metal compounds that contain cyclopentadienyl (Cp) or Cp derivative ligands (see U.S. Pat. No. 4,542,199). Non-metallocene single-site catalysts contain ligands other than Cp, usually heteroatomic ligands, e.g., boraaryl (see U.S. Pat. No. 6,034,027), pyrrolyl (see U.S. Pat. No. 5,539,124), azaborolinyl (see U.S. Pat. No. 5,756,611) and quinolinyl (see U.S. Pat. No. 5,637,660). Single-site catalysts typically produce polyethylenes having narrower molecular distributions. [0014] Densities of polyethylene base resin(s) can range from about 0.890 up to about 0.970 g/cm.sup.3; however, for most applications the base resins will have densities from 0.905 to 0.965 g/cm.sup.3. Densities reported herein are determined in accordance with ASTM D 1505. Melt indexes (MIs) of the polyethylene base resin(s), determined in accordance with ASTM D 1238-01, condition 190/2.16, typically range from 0.01 to 50 g/10 min and, more preferably, from 0.1 to 30 g/10 min. [0015] Other polymers which can be included in the base resin in minor amounts include copolymers of ethylene with comonomers containing polar groups such as C.sub.1-4 alkyl esters of acrylic and methacrylic acids and vinyl esters of C.sub.2-4 aliphatic acids. Such copolymers typically contain 1 to 35 weight percent and, more preferably, 2 to 25 weight percent polar comonomer. Included by way of illustration are ethylene-vinyl acetate copolymers, ethylene-methyl acrylate copolymers and ethylene-n-butyl acrylate copolymers. When the base resin is a mixture of polyethylene with copolymers of the above type, the copolymer will not exceed 40 weight percent of the base resin mixture. Preferably, such copolymers will comprise from 2 up to about 35 weight percent and, more preferably, 2 to 30 weight percent of the base resin. [0016] In a highly useful embodiment of the invention the polyethylene base resin is an ethylene-C.sub.3-8 .alpha.-olefin copolymer and, most preferably, an LLDPE or HDPE resin. [0017] Useful LLDPE resins are typically produced by the copolymerization of ethylene with one or more C.sub.3-8 .alpha.-olefin comonomers using transition metal catalysts in accordance with well-known processes and are characterized by linear molecules having no long-chain branching. Short-chain branching is instead present and is one of the primary determinants of resin density and physical properties. Useful LLDPEs have densities from 0.890 to 0.930 g/cm.sup.3 and, more preferably, from 0.906 to 0.930 g/cm.sup.3. MIs are typically in the range 0.1 to 10 g/10 min. and, more preferably, from 0.5 to 5 g/10 min. Linear low density polyethylene resins produced using metallocene catalysts, i.e., mLLDPEs, may also be used for the base resin component. LLDPE resins of the above types are highly useful for the production of blown and cast films and, when modified in accordance with the invention, the resulting films exhibit improved printability, i.e., good adhesion, with commonly used inks without surface treatment. [0018] Comonomers typically copolymerized with ethylene to obtain LLDPEs useful for the invention include 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and mixtures thereof. By incorporating these comonomers, linear polymer molecules having short-chain branches along the polymer backbone are produced. The amount of comonomer will typically not exceed 35 weight percent and, most commonly, the comonomer comprises from about 2 to 25 weight percent of the LLDPE polymer composition. The specific comonomer or comonomer mixture used is primarily based on process compatibility and the desired resin specifications. LLDPE resins which are copolymers of ethylene and butene-1 and/or hexene-1 are particularly advantageous. For best processability and ease of extrusion of blown films, it is advantageous to use LLDPEs having molecular weight distributions (MWDs) greater than 3. MWD is determined from the weight average molecular weight (Mw) and number average molecular weight (Mn) which are obtained by gel permeation chromatography. MWD=Mw/Mn. LLDPEs useful for the invention are available from commercial sources. [0019] HDPE resins are similarly produced by the copolymerization of ethylene with one or more C.sub.3-8 .alpha.-olefin comonomers with butene-1 and hexene-1 being preferred. Useful HDPEs will have densities in the range 0.941 to 0.970 g/cm.sup.3 and, more typically, from 0.945 to 0.965 g/cm.sup.3. In view of the high stiffness of HDPE resins, they are the base resins of choice for injection molding and blow molding applications and, when modified in accordance with the invention, can be used for the manufacture of molded articles having printable surfaces. MIs of the HDPE range from 0.02 to 50 g/10 min. and, most preferably, from 0.05 to 15 g/10 min. [0020] In another highly useful embodiment, particularly where the compositions are to be employed for extrusion coatings, the polyethylene base resin is an LDPE resin. The LDPEs will preferably have densities in the range 0.910 to 0.930 g/cm.sup.3 and MIs from about 0.5 to 20 g/10 min. [0021] Polyethylene glycols (PEGs) employed for the invention can be any of several condensation polymers of ethylene glycol known to the art and having average molecular weights from about 500 up to about 20000. PEGs having molecular weights in the range from about 1000 up to about 6000 are particularly advantageous. PEGs having molecular weights and molecular weight distributions suitable for use for the compositions of the invention are commercially available. Continue reading about Polyethylene compositions having improved printability... Full patent description for Polyethylene compositions having improved printability Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Polyethylene compositions having improved printability patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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